Lapping machine



Ma 10; 1949. R, K. KINA'RD 2,469,563

mrrme MACHINE FiledApril 4, 1947 3 Sheets-Sheet 1 FIG.

IN l/EN TOR R. x. mmno ATTORNEY R. K- KINARD LAPPING MACHINE May 10,1949 Filed April 4, 1947 3 Sheets-Sheet 2 FIG. 2

a a g 4 3 m F INVEN TOR,

. n. min/MR0 47 TORNEY y 1949. R. K. KINARD 2,469,563

I LAPPING MACHINE- Filed April 4, 1947 :5 Sheets-Sheet s FIG. 4.

INVENTOR R. K/NARD BYIM .4 r ran/var Patented May 10, 1949 UNITED STATESPATENT OFFICE LAPPING MACHINE Robert K. Kins-rd, Allentown, Pa, designerto.

Western Electric Company, Incorporated, New York, N. Y;, a corporationof New York Application April 4, 1947, Serial No. 739,437

scams. 51-120) extremely thin quartz crystal slices for use inelectrical arts.

For various uses in electrical arts, it is necessaryto employ smallslices of crystalline quartz having their fiat faces formed parallelwith each other to an extreme degree of accuracy and the slices beingfurther formed to a predetermined thickness with great accuracy. Suchslices are rough cut and formed in-various ways and are subsequentlyground or cut to approximately the desired thickness. The final step oflapping these nearly finished slices down to the finished product is adifiicult task, especially on a production basis. The most popularmethod of lapping quartz crystal slices includes a carrier or lappingnest comprising a metal disc oscillated between lapping plates suppliedwith an abrasive material, the carrier or nest having apertures thereinto receive and control the movement'of the slices between the lappingplates. The carrier or lapping nest of necessity had to be thinner thanthe final thickness desired for the quartz slices and also sufiicientlydurable to be driven to move the numerous quartz slices between thelapping plates. 7

Recently quartz crystal slices of a finer thickness than heretoforrequired have been requested for electrical units. approximately 25microns and the crystal slices of this thickness could not be producedby the present lapping machines and methods. A lapping nest of athickness suitable to accommodate these slices would not be suilicientlydurable to be driven between the conventional lapping plates.

An object of the invention is to provide an improved apparatus forsimultaneously lapping both sides of each of a plurality of thin objectsto produce, to a high degree of accuracy, parallel plane faces spaced apredetermined distance apart.

With the above and other objects in view, the invention comprises a,lapping machine.including an element formed with a plurality of lappingsurfaces surrounded by a retaining element and cooperating with arelatively movable'lapping plate to lap objects disposed on the lappingsurface. More specifically, the lapping machine includes a stationaryelement having a circular arrangement of vertically extending lappingmembers, cylindrical in general contour,'equallyspaced from each otherand having hardened gridded upper surfaces. A retaining element an-This' new thickness is 2 nular in general contour has a series ofopenings to receive the projections, the upper surface of the retainingelement being positioned a given distance above and parallel with acommon plane in which the gridded surfaces are disposed, this distancebeing less than the final thickness of the objects. A lapping plate issupported loosely.

upon the objects to be lapped and is oscillated relative to the lappingmembers, additional means being provided to create an additional motionin the lapping plate to vary the portions of the gridded under surfacethereof which come in contact with .the objects being lapped.

Other objects and advantages will be apparent from the followingdetailed description when considered in conjunctionwith the accompanyingdrawings, wherein v Fi 1 is a vertical sectional species of theinvention;

Fig. 2 is a fragmentary top plan view. of the structure shown in Fig. 1,portions thereof being broken away; I

view of one of the Fig. 3 is a fragmentary sectional view taken alongthe line 3-8 of Fig. 2; and

Fig. 4 is a vertical sectional view of another species of the invention.

Referring now to the drawings, attention is first directed to Figs. 1 to3, inclusive. The species of the invention shown in'these figuresincludes a supporting frame It having a saucer shaped table II mountedthereon with central bosses l2 and Il positioned about a centralaperture [5 for a shaft l8. Anv annular element l8 formed with aplurality of cylindrical lapping members is formed integral therewith ismounte'd centrally of the table 'I I.

The upper surfaces of the lapping members I! are hardened and ground tolie in a common plane, these surfaces also being gridded as at 20. Aretaining element 2|, annular ingeneral contour has a series ofapertures 22 therein substantially equal in diameter to the diameter ofeach of the lapping members is to receive these members as illustratedin Figs. 1 and 2. The

thickness of the retaining element 2! is slightly der surface I of thelapping plate is hardened and gridded in the conventional manner asindicated at 21.

The driving means for the lapping plate 25 includes the shaft II whichis journalled in bearin s 22 and 30 within the bosses l2 and i4 and thecentral aperture I! of the table ii. The shaft i is further supported bya. thrust bearing 2| disposed in a lateral member 22 of the main frameI0. A beveled gear 33 mounted upon the shaft i0 is driven from a maindrive shaft 24 through a beveled gear 25. A collar or head 26 mountedupon the upper end of the shaft i8 carries a pin 21 eccentricallymounted to move in acircular path, the diameter of which issubstantially equal to the diameter of each of outwardly in thisdirection during each cycle of I movement. The roller 4| is supported byan arm 42, slidably disposed in an aperture 43 of a holder 44, limitedin its movement by a pin 45 and normally urged outwardly by a spring 46,the spring functioning to cushion the contact between any of the teeth40 of the lapping plate and the roller 4 I.

Prior to considering the operation of the machine, attention is directedto the objects 50 which are to represent quartz crystal slices to bereduced in thickness by this machine to approximately 25 microns. Theobjects 50 in reality are slightly thicker than the required finaldimension beforethey are placed in their respective pockets on thelapping members it. It will be observed therefore that the dimensions ofthe objects 50, the distances between the upper surfaces of the lappingmembers I! and the retaining element also to illustrate the existence ofparts 50 within these pockets. The lapping machine as illustrated in thedrawings is of necessity smaller than the actual machine. It would notbe possible to show the objects 52 in the drawings with their exactthickness and the same applies to the illustration of the depth of thepockets receiving the objects and the space between the lappingsurfaces.

In preparing the machine for operation the lapping plate 25 is removedand an object, namely, a quartz crystal slice II, is placed within eachof the pockets. that is, the apertures 22 above the gridded surfaces ofthe lapping members l9. The lapping plate 25 is then carefully loweredin place and the conventional abrasive material is supplied in the usualmanner to the lapping areas during operation of the machine. The saucershaped formation of the table if is to receive the abrasive materialand-direct it in the usual man-. ner to the supply (not shown). Themachine is then set in operation by driving the shaft 34, causingrotation of the shaft l 6 through the gears 22 and 25, causing the pin21 to move in its circular path about the centeriine of the shaft it tooscillate the lapping plate 22 relative to the lapping members it; Thisaction will cause both lapping surfaces adjacent each object II to grindaway the surfaces of the object through the assistance of the abrasivematerial, maintaining the surfaces parallel with each other. Each timethe lap ng plate 25 approaches the roller H, the roller will engage oneof the teeth and act as a fulcrum for the lapping plate during thecontinued movement applied to the lapping plate through the pin 21,creating intermittent adjustments in the lapping plate relative to thelapping portions I9.

The species ofv the invention shown in Fig. 4 is identical in everydetail to that shown in Figs. 1 and 2 with the exception of the drivingmeans for the lapping plate, like reference numerals being applied tothe like parts. The lapping plate in this figure is given the referencenumeral 65, although it differs from the lapping plate 25 only in itsconnection with the driving means. The driving means in this instanceincludes a hollow shaft 56 journalled in a suitable bearing 51 and keyedto a pulley 58 driven by a belt 59 from a power means (not shown). Ifdesired, the driving means may include a drive shaft operativelyconnected to the shaft 88 through the aid of gears as illustrated inFig. 1. An arm 60 is keyed to the upper end of the shaft 58 and supportsa pin iii in the form of a shaft. the lower end of which is journalledin a-bearing 82 of the arm 60. The axes of the shafts I6 and H areparallel with each other and disposed a given distance apart whichissubstantially equal the radius of the lapping members it. A gear 64fixedly mounted upon the pin or shaft 8| interengages a pinion 85 whichis mounted upon the upper end of a fixed shaft 66 extending through thehollow shaft 56 into an apertured portion 21 of a lateral member 68 ofthe mainframe ill. The aperture 69 is internally splined to receive thesplined end 10 of the shaft 66. Returning now to the shaft 6|, it willbe observed that, the upper end thereof is grooved at 12 to receive anapertured end of an arm "which is pivotally connected at 14 to the shaftiii. The outer end of the arm 13 is bent downwardly at right angles asindicated'at l5 and is receivable in an aperture 18 in the lapping plate55.

During operation of this species of the invention, through the drivingof the belt 52, the hollow shaft 58 will be rotated about the stationaryshaft 86 moving the pin or shaft ii in a circuitous path to impart acircular or oscillating motion to the lapping plate 55 relative to thelapping members l9 and the objects II. As the arm carries the shaft Siin its circuitous path, the gear '64 travels about the pinion I and inengagement therewith to cause the shaft H to rotate slowly. In thisvmanner,- there is a continuous change in the portions of the griddedsurface 18 of the lapping plate 55 which come in contact with thevarious objects 50 to cause uniform wear on the lapping surface 18.Through this driving mechanismthe same circular motion is imparted tothe lapping plate 55 as is applied to the lapping plate 25 of thestructure shown in Figs. 1 and 2. The .only difference in the motions ofthe two lapping plates is that the adjusting motion of the lapping plate55 is continuous while the adjusting motion of the lapping plate 25 isintermittent.

With these structures, their principal features being identical in theprovision of a plurality of fixed position lapping members withretaining pockets for the individual objects or thin quartz crystalslices, it 'is possible to reduce the thickness of these objects to finedimensions while maintainingtheir faces or opposing surfacessubstantially parallel. sions attained through this lapping processthrough the aid of the species of the lapping machine is made possiblemainly through the sturdy structures, forming the pockets andcontrolling the positioning of the quartz slices within their individuallapping areas. Furthermore, the lapping members, being integral withtheir base l8, may be simultaneously reconditioned and their surfacesmaintained in a common plane. The retaining element 2| may bereconditioned in a similar manner grinding the upper surface thereof tomaintain the depth of the pockets surrounding tliegridded surfaces 20.Furthermore, the depth of the pockets may be varied by the introductionof shims between the abutting surfinal thickness to which articlesdisposed individually in the pockets are to be lapped, a lapping elementpositioned above the lapping members and having a gridded under surfaceto The fineness in the dimenfaces of the retaining element 2| and thebase l8 of the lapping members l9.

Although specific improvements of the invention have been shown anddescribed, it will bev opposite faces of thin articles comprising a plu-I rality of lapping members disposed in circular arrangement at spacedpositions with respect to each other and having upper surfaces toreceive articles to be lapped, -means surrounding the lapping members toform retaining pockets above the upper surfaces of their respectivelapping members of like depths less than the final thickness to whichthe articles are to be lapped, a lapping element positioned above thelapping members and having an under surface to engageall the articlessimultaneously, and means' to rest on all the articles in the pocketssimultaneously, and means to move the lapping element relative to thelapping members to lap the articles as they are individually retained intheir respective pockets.

3. An apparatus for simultaneously lapping opposite faces of thinarticles comprising a stationary support, an annular element mounted onthe support and having integral lapping members circular incross-section disposed in spaced positions circularly about the uppersurface ofthe annular element with their upper surfaces gridded andpositioned in a given plane parallel with the upper surface of theannular element, an annular retaining member, having a circulararrangement of cylindrical apertures therein to receive their respectivelapping members, mounted on the upper surface of theannular element andbeing of greater vertical dimension than the lapping members wherebyretaining.

pockets formed in the apertures extend above the gridded surfaces oflike distances less than the final thickness to which. articles disposedindi-.

vvidually inthe pockets are to be. lapped, a

lapping element positioned above the lapping members and having agridded under surface to rest on all the articles inthe pocketssimultaneously, spaced projections mounted on the periphsupport to beengaged by certain of the projecmove the lapping element about.an axisin .a I

path the diameter of which is substantially equal the diameter of eachof the upper surfaces of the lapping members.

2. An apparatus for simultaneously lapping.

opposite faces of thin articles comprising a stationary support, anannular element mounted on the support and having integral lappingmembers tions during each cycle of movement of the lapping element toimpart further movement to the lapping element ,to vary the portions ofthe under surface of the lapping element engaging the articles to causeuniform wear on the said surface.

' ROBERT K. KINARD.

REFERENCES CITED,

The following references are of record in the file of this patent

